package org.mm.proxycache.util.collections;

import java.util.Collections;
import java.util.Comparator;
import java.util.Map;
import java.util.SortedMap;

/*
 * @(#)NavigableMap.java    1.6 06/05/10
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/**
 * A {@link SortedMap} extended with navigation methods returning the closest
 * matches for given search targets. Methods {@code lowerEntry},
 * {@code floorEntry}, {@code ceilingEntry}, and {@code higherEntry} return
 * {@code Map.Entry} objects associated with keys respectively less than, less
 * than or equal, greater than or equal, and greater than a given key, returning
 * {@code null} if there is no such key. Similarly, methods {@code lowerKey},
 * {@code floorKey}, {@code ceilingKey}, and {@code higherKey} return only the
 * associated keys. All of these methods are designed for locating, not
 * traversing entries.
 * 
 * <p>
 * A {@code NavigableMap} may be accessed and traversed in either ascending or
 * descending key order. The {@code descendingMap} method returns a view of the
 * map with the senses of all relational and directional methods inverted. The
 * performance of ascending operations and views is likely to be faster than
 * that of descending ones. Methods {@code subMap}, {@code headMap}, and
 * {@code tailMap} differ from the like-named {@code SortedMap} methods in
 * accepting additional arguments describing whether lower and upper bounds are
 * inclusive versus exclusive. Submaps of any {@code NavigableMap} must
 * implement the {@code NavigableMap} interface.
 * 
 * <p>
 * This interface additionally defines methods {@code firstEntry},
 * {@code pollFirstEntry}, {@code lastEntry}, and {@code pollLastEntry} that
 * return and/or remove the least and greatest mappings, if any exist, else
 * returning {@code null}.
 * 
 * <p>
 * Implementations of entry-returning methods are expected to return
 * {@code Map.Entry} pairs representing snapshots of mappings at the time they
 * were produced, and thus generally do <em>not</em> support the optional
 * {@code Entry.setValue} method. Note however that it is possible to change
 * mappings in the associated map using method {@code put}.
 * 
 * <p>
 * Methods {@link #subMap(Object, Object) subMap(K, K)},
 * {@link #headMap(Object) headMap(K)}, and {@link #tailMap(Object) tailMap(K)}
 * are specified to return {@code SortedMap} to allow existing implementations
 * of {@code SortedMap} to be compatibly retrofitted to implement
 * {@code NavigableMap}, but extensions and implementations of this interface
 * are encouraged to override these methods to return {@code NavigableMap}.
 * Similarly, {@link #keySet()} can be overriden to return {@code NavigableSet}.
 * 
 * <p>
 * This interface is a member of the <a href="{@docRoot}/../technotes/guides/collections/index.html">
 * Java Collections Framework</a>.
 * 
 * @author Doug Lea
 * @author Josh Bloch
 * @param <K>
 *            the type of keys maintained by this map
 * @param <V>
 *            the type of mapped values
 * @since 1.6
 */
public interface NavigableMap<K, V> extends SortedMap<K, V>
{
    /**
     * Returns a key-value mapping associated with the greatest key strictly
     * less than the given key, or {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return an entry with the greatest key less than {@code key}, or
     *         {@code null} if there is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    Map.Entry<K, V> lowerEntry( K key );

    /**
     * Returns the greatest key strictly less than the given key, or
     * {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return the greatest key less than {@code key}, or {@code null} if there
     *         is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    K lowerKey( K key );

    /**
     * Returns a key-value mapping associated with the greatest key less than or
     * equal to the given key, or {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return an entry with the greatest key less than or equal to {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    Map.Entry<K, V> floorEntry( K key );

    /**
     * Returns the greatest key less than or equal to the given key, or
     * {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return the greatest key less than or equal to {@code key}, or
     *         {@code null} if there is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    K floorKey( K key );

    /**
     * Returns a key-value mapping associated with the least key greater than or
     * equal to the given key, or {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return an entry with the least key greater than or equal to {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    Map.Entry<K, V> ceilingEntry( K key );

    /**
     * Returns the least key greater than or equal to the given key, or
     * {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return the least key greater than or equal to {@code key}, or
     *         {@code null} if there is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    K ceilingKey( K key );

    /**
     * Returns a key-value mapping associated with the least key strictly
     * greater than the given key, or {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return an entry with the least key greater than {@code key}, or
     *         {@code null} if there is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    Map.Entry<K, V> higherEntry( K key );

    /**
     * Returns the least key strictly greater than the given key, or
     * {@code null} if there is no such key.
     * 
     * @param key
     *            the key
     * @return the least key greater than {@code key}, or {@code null} if there
     *         is no such key
     * @throws ClassCastException
     *             if the specified key cannot be compared with the keys
     *             currently in the map
     * @throws NullPointerException
     *             if the specified key is null and this map does not permit
     *             null keys
     */
    K higherKey( K key );

    /**
     * Returns a key-value mapping associated with the least key in this map, or
     * {@code null} if the map is empty.
     * 
     * @return an entry with the least key, or {@code null} if this map is empty
     */
    Map.Entry<K, V> firstEntry();

    /**
     * Returns a key-value mapping associated with the greatest key in this map,
     * or {@code null} if the map is empty.
     * 
     * @return an entry with the greatest key, or {@code null} if this map is
     *         empty
     */
    Map.Entry<K, V> lastEntry();

    /**
     * Removes and returns a key-value mapping associated with the least key in
     * this map, or {@code null} if the map is empty.
     * 
     * @return the removed first entry of this map, or {@code null} if this map
     *         is empty
     */
    Map.Entry<K, V> pollFirstEntry();

    /**
     * Removes and returns a key-value mapping associated with the greatest key
     * in this map, or {@code null} if the map is empty.
     * 
     * @return the removed last entry of this map, or {@code null} if this map
     *         is empty
     */
    Map.Entry<K, V> pollLastEntry();

    /**
     * Returns a reverse order view of the mappings contained in this map. The
     * descending map is backed by this map, so changes to the map are reflected
     * in the descending map, and vice-versa. If either map is modified while an
     * iteration over a collection view of either map is in progress (except
     * through the iterator's own {@code remove} operation), the results of the
     * iteration are undefined.
     * 
     * <p>
     * The returned map has an ordering equivalent to
     * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.
     * The expression {@code m.descendingMap().descendingMap()} returns a view
     * of {@code m} essentially equivalent to {@code m}.
     * 
     * @return a reverse order view of this map
     */
    NavigableMap<K, V> descendingMap();

    /**
     * Returns a {@link NavigableSet} view of the keys contained in this map.
     * The set's iterator returns the keys in ascending order. The set is backed
     * by the map, so changes to the map are reflected in the set, and
     * vice-versa. If the map is modified while an iteration over the set is in
     * progress (except through the iterator's own {@code remove} operation),
     * the results of the iteration are undefined. The set supports element
     * removal, which removes the corresponding mapping from the map, via the
     * {@code Iterator.remove}, {@code Set.remove}, {@code removeAll},
     * {@code retainAll}, and {@code clear} operations. It does not support the
     * {@code add} or {@code addAll} operations.
     * 
     * @return a navigable set view of the keys in this map
     */
    NavigableSet<K> navigableKeySet();

    /**
     * Returns a reverse order {@link NavigableSet} view of the keys contained
     * in this map. The set's iterator returns the keys in descending order. The
     * set is backed by the map, so changes to the map are reflected in the set,
     * and vice-versa. If the map is modified while an iteration over the set is
     * in progress (except through the iterator's own {@code remove} operation),
     * the results of the iteration are undefined. The set supports element
     * removal, which removes the corresponding mapping from the map, via the
     * {@code Iterator.remove}, {@code Set.remove}, {@code removeAll},
     * {@code retainAll}, and {@code clear} operations. It does not support the
     * {@code add} or {@code addAll} operations.
     * 
     * @return a reverse order navigable set view of the keys in this map
     */
    NavigableSet<K> descendingKeySet();

    /**
     * Returns a view of the portion of this map whose keys range from
     * {@code fromKey} to {@code toKey}. If {@code fromKey} and {@code toKey}
     * are equal, the returned map is empty unless {@code fromExclusive} and
     * {@code toExclusive} are both true. The returned map is backed by this
     * map, so changes in the returned map are reflected in this map, and
     * vice-versa. The returned map supports all optional map operations that
     * this map supports.
     * 
     * <p>
     * The returned map will throw an {@code IllegalArgumentException} on an
     * attempt to insert a key outside of its range, or to construct a submap
     * either of whose endpoints lie outside its range.
     * 
     * @param fromKey
     *            low endpoint of the keys in the returned map
     * @param fromInclusive
     *            {@code true} if the low endpoint is to be included in the
     *            returned view
     * @param toKey
     *            high endpoint of the keys in the returned map
     * @param toInclusive
     *            {@code true} if the high endpoint is to be included in the
     *            returned view
     * @return a view of the portion of this map whose keys range from
     *         {@code fromKey} to {@code toKey}
     * @throws ClassCastException
     *             if {@code fromKey} and {@code toKey} cannot be compared to
     *             one another using this map's comparator (or, if the map has
     *             no comparator, using natural ordering). Implementations may,
     *             but are not required to, throw this exception if
     *             {@code fromKey} or {@code toKey} cannot be compared to keys
     *             currently in the map.
     * @throws NullPointerException
     *             if {@code fromKey} or {@code toKey} is null and this map does
     *             not permit null keys
     * @throws IllegalArgumentException
     *             if {@code fromKey} is greater than {@code toKey}; or if this
     *             map itself has a restricted range, and {@code fromKey} or
     *             {@code toKey} lies outside the bounds of the range
     */
    NavigableMap<K, V> subMap( K fromKey, boolean fromInclusive, K toKey, boolean toInclusive );

    /**
     * Returns a view of the portion of this map whose keys are less than (or
     * equal to, if {@code inclusive} is true) {@code toKey}. The returned map
     * is backed by this map, so changes in the returned map are reflected in
     * this map, and vice-versa. The returned map supports all optional map
     * operations that this map supports.
     * 
     * <p>
     * The returned map will throw an {@code IllegalArgumentException} on an
     * attempt to insert a key outside its range.
     * 
     * @param toKey
     *            high endpoint of the keys in the returned map
     * @param inclusive
     *            {@code true} if the high endpoint is to be included in the
     *            returned view
     * @return a view of the portion of this map whose keys are less than (or
     *         equal to, if {@code inclusive} is true) {@code toKey}
     * @throws ClassCastException
     *             if {@code toKey} is not compatible with this map's comparator
     *             (or, if the map has no comparator, if {@code toKey} does not
     *             implement {@link Comparable}). Implementations may, but are
     *             not required to, throw this exception if {@code toKey} cannot
     *             be compared to keys currently in the map.
     * @throws NullPointerException
     *             if {@code toKey} is null and this map does not permit null
     *             keys
     * @throws IllegalArgumentException
     *             if this map itself has a restricted range, and {@code toKey}
     *             lies outside the bounds of the range
     */
    NavigableMap<K, V> headMap( K toKey, boolean inclusive );

    /**
     * Returns a view of the portion of this map whose keys are greater than (or
     * equal to, if {@code inclusive} is true) {@code fromKey}. The returned
     * map is backed by this map, so changes in the returned map are reflected
     * in this map, and vice-versa. The returned map supports all optional map
     * operations that this map supports.
     * 
     * <p>
     * The returned map will throw an {@code IllegalArgumentException} on an
     * attempt to insert a key outside its range.
     * 
     * @param fromKey
     *            low endpoint of the keys in the returned map
     * @param inclusive
     *            {@code true} if the low endpoint is to be included in the
     *            returned view
     * @return a view of the portion of this map whose keys are greater than (or
     *         equal to, if {@code inclusive} is true) {@code fromKey}
     * @throws ClassCastException
     *             if {@code fromKey} is not compatible with this map's
     *             comparator (or, if the map has no comparator, if
     *             {@code fromKey} does not implement {@link Comparable}).
     *             Implementations may, but are not required to, throw this
     *             exception if {@code fromKey} cannot be compared to keys
     *             currently in the map.
     * @throws NullPointerException
     *             if {@code fromKey} is null and this map does not permit null
     *             keys
     * @throws IllegalArgumentException
     *             if this map itself has a restricted range, and
     *             {@code fromKey} lies outside the bounds of the range
     */
    NavigableMap<K, V> tailMap( K fromKey, boolean inclusive );

    /**
     * {@inheritDoc}
     * 
     * <p>
     * Equivalent to {@code subMap(fromKey, true, toKey, false)}.
     * 
     * @throws ClassCastException
     *             {@inheritDoc}
     * @throws NullPointerException
     *             {@inheritDoc}
     * @throws IllegalArgumentException
     *             {@inheritDoc}
     */
    SortedMap<K, V> subMap( K fromKey, K toKey );

    /**
     * {@inheritDoc}
     * 
     * <p>
     * Equivalent to {@code headMap(toKey, false)}.
     * 
     * @throws ClassCastException
     *             {@inheritDoc}
     * @throws NullPointerException
     *             {@inheritDoc}
     * @throws IllegalArgumentException
     *             {@inheritDoc}
     */
    SortedMap<K, V> headMap( K toKey );

    /**
     * {@inheritDoc}
     * 
     * <p>
     * Equivalent to {@code tailMap(fromKey, true)}.
     * 
     * @throws ClassCastException
     *             {@inheritDoc}
     * @throws NullPointerException
     *             {@inheritDoc}
     * @throws IllegalArgumentException
     *             {@inheritDoc}
     */
    SortedMap<K, V> tailMap( K fromKey );
}
